Short Answer 
Dalton’s Law of Partial Pressures states that the total pressure of a gas mixture is the sum of the partial pressures of each gas. By identifying the total pressure and the partial pressure of one gas, you can solve for the unknown partial pressure; in this case, the partial pressure of hydrogen was determined to be 741 torr.
Step 1: Understand Dalton’s Law of Partial Pressures
Dalton’s Law states that the total pressure of a gas mixture is the sum of the partial pressures of each individual gas component. This means that every gas contributes to the overall pressure in the container. The formula representing this law is:
- ‚à ë P = P1 + P2
Step 2: Identify the Variables
To use Dalton’s Law, we need to identify the pressures involved in our situation. For example, in this case, we have:
- ‚à ë P (total pressure) = 765 torr
- P1 (partial pressure of water) = 24 torr
- P2 (partial pressure of hydrogen) = ?
Step 3: Solve for the Unknown Pressure
We can rearrange the formula to find the partial pressure of hydrogen. Substituting the known values gives us:
- P2 = ‚à ë P – P1
- P2 = 765 torr – 24 torr
- P2 = 741 torr
This means the pressure inside the tube due to hydrogen gas is 741 torr. This result ultimately illustrates how Dalton’s Law is applied to determine individual gas pressures in mixtures.